From: Ian Campbell <ian.campbell@citrix.com>

libxl: attempt to cleanup tapdisk processes on disk backend destroy.

This patch properly terminates the tapdisk2 process(es) started
to service a virtual block device.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

xen-unstable changeset: 23883:7998217630e2
xen-unstable date: Wed Sep 28 16:42:11 2011 +0100
Signed-off-by: Greg Wettstein <greg@enjellic.com>
Backport-requested-by: Greg Wettstein <greg@enjellic.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

6 files changed, 51 insertions, 11 deletions

diff --git a/tools/blktap2/control/tap-ctl-list.c b/tools/blktap2/control/tap-ctl-list.c
index 1497270874..c91f6f48d3 100644
--- a/tools/blktap2/control/tap-ctl-list.c
+++ b/tools/blktap2/control/tap-ctl-list.c
@@ -506,17 +506,15 @@ out:
 }
 
 int
-tap_ctl_find_minor(const char *type, const char *path)
+tap_ctl_find(const char *type, const char *path, tap_list_t *tap)
 {
 	tap_list_t **list, **_entry;
-	int minor, err;
+	int ret = -ENOENT, err;
 
 	err = tap_ctl_list(&list);
 	if (err)
 		return err;
 
-	minor = -1;
-
 	for (_entry = list; *_entry != NULL; ++_entry) {
 		tap_list_t *entry  = *_entry;
 
@@ -526,11 +524,13 @@ tap_ctl_find_minor(const char *type, const char *path)
 		if (path && (!entry->path || strcmp(entry->path, path)))
 			continue;
 
-		minor = entry->minor;
+		*tap = *entry;
+		tap->type = tap->path = NULL;
+		ret = 0;
 		break;
 	}
 
 	tap_ctl_free_list(list);
 
-	return minor >= 0 ? minor : -ENOENT;
+	return ret;
 }
diff --git a/tools/blktap2/control/tap-ctl.h b/tools/blktap2/control/tap-ctl.h
index d951e774cb..de0bc29a48 100644
--- a/tools/blktap2/control/tap-ctl.h
+++ b/tools/blktap2/control/tap-ctl.h
@@ -76,7 +76,7 @@ int tap_ctl_get_driver_id(const char *handle);
 
 int tap_ctl_list(tap_list_t ***list);
 void tap_ctl_free_list(tap_list_t **list);
-int tap_ctl_find_minor(const char *type, const char *path);
+int tap_ctl_find(const char *type, const char *path, tap_list_t *tap);
 
 int tap_ctl_allocate(int *minor, char **devname);
 int tap_ctl_free(const int minor);
diff --git a/tools/libxl/libxl_blktap2.c b/tools/libxl/libxl_blktap2.c
index b238a0a7ca..00d8dbbee4 100644
--- a/tools/libxl/libxl_blktap2.c
+++ b/tools/libxl/libxl_blktap2.c
@@ -18,6 +18,8 @@
 
 #include "tap-ctl.h"
 
+#include <string.h>
+
 int libxl__blktap_enabled(libxl__gc *gc)
 {
     const char *msg;
@@ -30,12 +32,13 @@ const char *libxl__blktap_devpath(libxl__gc *gc,
 {
     const char *type;
     char *params, *devname = NULL;
-    int minor, err;
+    tap_list_t tap;
+    int err;
 
     type = libxl__device_disk_string_of_format(format);
-    minor = tap_ctl_find_minor(type, disk);
-    if (minor >= 0) {
-        devname = libxl__sprintf(gc, "/dev/xen/blktap-2/tapdev%d", minor);
+    err = tap_ctl_find(type, disk, &tap);
+    if (err == 0) {
+        devname = libxl__sprintf(gc, "/dev/xen/blktap-2/tapdev%d", tap.minor);
         if (devname)
             return devname;
     }
@@ -49,3 +52,28 @@ const char *libxl__blktap_devpath(libxl__gc *gc,
 
     return NULL;
 }
+
+
+void libxl__device_destroy_tapdisk(libxl__gc *gc, char *be_path)
+{
+    char *path, *params, *type, *disk;
+    int err;
+    tap_list_t tap;
+
+    path = libxl__sprintf(gc, "%s/tapdisk-params", be_path);
+    if (!path) return;
+
+    params = libxl__xs_read(gc, XBT_NULL, path);
+    if (!params) return;
+
+    type = params;
+    disk = strchr(params, ':');
+    if (!disk) return;
+
+    *disk++ = '\0';
+
+    err = tap_ctl_find(type, disk, &tap);
+    if (err < 0) return;
+
+    tap_ctl_destroy(tap.id, tap.minor);
+}
diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index ccc45348ae..7e8fcef20d 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -250,6 +250,7 @@ int libxl__device_destroy(libxl_ctx *ctx, char *be_path, int force)
     if (!state)
         goto out;
     if (atoi(state) != 4) {
+        libxl__device_destroy_tapdisk(&gc, be_path);
         xs_rm(ctx->xsh, XBT_NULL, be_path);
         goto out;
     }
@@ -368,6 +369,7 @@ int libxl__devices_destroy(libxl_ctx *ctx, uint32_t domid, int force)
             }
         }
     }
+    libxl__device_destroy_tapdisk(&gc, be_path);
 out:
     libxl__free_all(&gc);
     return 0;
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 33f4adbab2..9cf503f20e 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -314,6 +314,12 @@ _hidden const char *libxl__blktap_devpath(libxl__gc *gc,
                                  const char *disk,
                                  libxl_disk_format format);
 
+/* libxl__device_destroy_tapdisk:
+ *   Destroys any tapdisk process associated with the backend represented
+ *   by be_path.
+ */
+_hidden void libxl__device_destroy_tapdisk(libxl__gc *gc, char *be_path);
+
 _hidden char *libxl__uuid2string(libxl__gc *gc, const libxl_uuid uuid);
 
 struct libxl__xen_console_reader {
diff --git a/tools/libxl/libxl_noblktap2.c b/tools/libxl/libxl_noblktap2.c
index 95fee973ed..274fc4d267 100644
--- a/tools/libxl/libxl_noblktap2.c
+++ b/tools/libxl/libxl_noblktap2.c
@@ -27,3 +27,7 @@ const char *libxl__blktap_devpath(libxl__gc *gc,
 {
     return NULL;
 }
+
+void libxl__device_destroy_tapdisk(libxl__gc *gc, char *be_path)
+{
+}